When you include a module position in your Joomla 1.5 template, the code looks something like this:

<jdoc:include type="modules" name="left" style="xhtml" /> 

This means that this is a module, with a position of left and a style of XHTML.  

You've been designing your new website, creating a template to your client's specifications. All is going well. They are making use of the weblinks component for publishing their list of favorite links. They call up and say, "we really don't like seeing those numbers in the left column, please take those away." Looking for all the available configuration options, you discover that you can do anything you want on that page except get rid of those pesky numbers!

Template overrides to the rescue!

Every component and module in Joomla has a particular snippet of code called a template, whose job is to generate HTML and nothing else. The Joomla framework is designed to allow templates to replace those snippets as needed. You can build a template that completely takes over the writing of almost all html on the site using these overrides.

One of the more exciting improvements in Joomla! 1.5 is the idea of template overrides. Joomla! templates can be thought of as a wrapper for displaying content produced by the various Joomla! components, modules and plugins/mambots. If you've ever created your own template, you know that there is special code you place throughout it to display that content. You can carefully create html according to your own exacting standards, but the results of all those modules in the left position, for example will still produce whatever html those modules were programmed to produce.

So let's say you've decided to create a website that does not use all those nested tables. You could create a Joomla! template that is all divs and no tables, but the individual Joomla! extensions will still be outputting those pesky nested tables.

With modules, you at least have the choice of using the tableless 'xhtml' style. But here again, the style attribute only tells Joomla! how to wrap the content produced by the module. The module itself may still be outputting table tags that you would rather not see used.